1. Field of Invention
This invention is directed to construction of ink tanks used in print engines such as, for example, ink jet printers.
2. Description of Related Art
Conventional ink tank designs typically have seals which are removed when the ink tank is placed into a print engine. These ink tanks have been known to experience problems with leakage of ink when the seal, such as, for example, a foil seal, is removed prior to placing the ink tanks into the print engine. The leakage problem is often exacerbated when the ink tank seal is removed at the somewhat relatively lower atmospheric pressure which exists at high altitude locations. Some conventional tanks have a number of ink reservoir chambers. Any air trapped inside of these one or more ink reservoir chambers expands, when the seal is removed and the tank is directly exposed to relatively lower atmospheric pressure, to reach pressure equilibrium with respect to the relatively lower ambient atmospheric pressure. This expansion of air inside of the formerly sealed ink tank occurs rapidly and causes a rapid surge of ink from the one or more ink reservoir chambers where the air is located into the ink tank foam chamber, where an ink supply opening is located. This ink moves via a path or paths of least resistance, which often includes the ink tank supply opening, resulting in ink dripping out of this opening from the ink tank.
Moreover, some conventional ink tanks tend to have relatively poor ink supply consistency and accuracy. In a typical application, an optical sensing system is used to detect when the ink in the ink tank falls below a certain level. In such ink tanks, the amount of ink delivered between the ink reservoir chambers and the ink foam chamber, where an ink supply opening is located, is important in order to provide an accurate measure of how much usable ink remains in the ink tank. The amount of ink remaining in the ink tank when sensed low can be unpredictable due to the variable density and resistance to fluid and air flow that is inherent with foam. In addition, if the resistance of the foam to air flow to the rear chamber is extreme, the ink tank may xe2x80x9cdeprimexe2x80x9d resulting in a severe defect on the customer""s print.
This invention provides an ink tank construction which reduces the leakage of ink from an ink tank when the protective seal is removed.
This invention separately provides an ink tank construction that is able to reduce the leakage of ink from an ink tank when the protective seal is removed at relatively high altitudes.
This invention separately provides an ink tank construction which provides a low impedance path to conduct the ink from an ink reservoir portion of the ink tank into a safe area of the tank.
This invention separately provides an ink tank construction that uses a low impedance path to determine and regulate the ink supply pressure of an ink tank to
In various exemplary embodiments of the ink tank construction according to this invention, this low impedance path comprises one or more pipes extending between an ink reservoir chamber and an ink supply chamber. In other various exemplary embodiments of the ink tank construction according to this invention, this low impedance path decouples the ink supply of ink to the ink supply chamber from the ink supply of ink from the ink supply chamber. This renders the ink supply consistency and accuracy less dependent on the known variability in density and ink flow resistance of foam.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.